Wait as minute here! There is no sensor if it is a 240D, in terms of an electrical sensor.
The gauge reads actual oil pressure at the filter cannister where pressure is coming from the engine, so I think maybe the oil pump is not getting oil in a sharp turn, the level may be lower than the dip stick indicates, or something else related to the oil.
I would certainly pursue this to prevent possible damage to the cam lobes or worse! In San Francisco a driver of a diesel once stopped on a steep incline at traffic light. The oil was low. After only a minute or two the engine started making a noise and ultimately it had to be torn down to fix the noise, according to a mechanic I know. I don't know if it was uphill or downhill but that removed oil long enough to score a bearing or something. my-two cents!
Dieseldiehard